Chapter 12
Conclusion
“...But since I designed to employ my whole life in the search after so necessary a science, and since I had fallen in with a path which seems to me such, that if any one follow it he must inevitably reach the end desired, unless he be hindered either by the shortness of life or the want of experiments, I judged that there could be no more effectual provision against these two impediments than if I were faithfully to communicate to the public all the little I might myself have found, and incite men of superior genius to strive to proceed farther, by contributing, each according to his inclination and ability, to the experiments which it would be necessary to make, and also by informing the public of all they might discover, so that, by the last beginning where those before them had left off, and thus connecting the lives and labours of many, we might collectively proceed much farther than each by himself could do”.
René Descartes (1596–1650)
Discourse on the method,
Chapter 6, 1637
For many years, ergonomists, researchers, and engineers have dreamt of offering the gift of ubiquity. Beyond the philosophical and psychological aspects, this can result in “wireless” connectivity everywhere for everyone, regardless of location or time.
This “wireless” connectivity can be improved by the integration of intermodality, such as augmented reality and virtual reality, requiring a large bandwidth or throughput with a significant bilateral precise tracking device.
Technical and commercial advances abound in this sense, with the success of more than two billion people communicating via cell phones and hundreds of millions of people every day using WiFi hotspots.
The conventional radio solutions (300 kHz–3,000 GHz) have so far met the expectations of customers. But due to increasing demand in throughput, spectral congestion becomes critical, not only in relation to the powers implemented and electricity consumption, but also in relation to the questions they raise for some users’ radio systems concerning the safety aspect [IAR 11].
An alternative is proposed by wireless optical technology using the infrared or visible spectral range. Its use has been developed in many areas of telecommunications: the remote control, the visible light communication (VLC), the free-space optical (FSO) links, intersatellite links, and indoor wireless optical links.
From a regulatory point of view, their implementation does not require any frequency authorization or any cost to get a license.
A techno-economic example, already commonly validated, is the infrared remote control.
Another validated techno-economic segment is the FSO links, which are an alternative to microwave links and to optical fiber cables to meet the growing needs of broadband telecommunications.
This solution uses low-power laser beams to ensure a negligible impact on the environment. The main advantages over optical fibers are their low cost, flexibility, installation, and deployment speed. No civil engineering works are required.
Availability of components (lasers, receivers, modulators, etc.) widely used in optical fiber telecommunications greatly reduces the cost of such equipment. Manufacturers today offer relevant systems whose interfaces match the industry standards (Gigabit Ethernet, for example) allowing the interconnection of local area network to remote sites.
Another contemporary application relates to intersatellite links for which low power consumption and small size favored the optical wireless solution instead of embedded radio systems.
The indoor wireless optical systems are entering a phase of commercial maturity in the visible spectrum (VLC) with applications such as broadcast information on mobile phones and data traffic in vehicles (ITS).
In the infrared spectrum, we are entering an industrial process with optronic choices and signal processing completion, incorporating the energy constraints and limited electrical/optical or optical/electrical conversion. Optimized data transfers even in emergency situations together with a network without coordinator have already been implemented in a protocol suitable to wireless optic (OWMAC).
Because, as an indoor network solution in a home or an office environment, this communication medium has many attractive opportunities:
– Visible and infrared spectral regions provide a bandwidth that is twice the size of the radio field, more than 700,000 GHz actually unregulated and untaxed.
– Optical transmissions are limited inside a room. This feature allows us to physically and easily secure each communication. It is also possible to use the same optical wavelength in the neighboring room or apartment with the same level of security. This facilitates and makes the network architecture intuitive.
– Because of the spectral range used, there is no possibility of suffered or produced interference with radio systems in the vicinity. Moreover, it is also possible to convert a portion of this photon energy into electrical energy.
Eventually, we can imagine an even more prospective scenario with access and connectivity between rooms. Wireless optical communication is achieved between a station per room and one or more smart objects in the room whose characteristics and format are mobile phone and laptop.
This objective using wireless optical communication with a positive energy balance provides the features mentioned above, together with a universal remote control, a pointing and localization device to provide an appropriate interface in augmented reality or mastered immersion in virtual reality.
This global photonic approach coupled with the depletion of rare earths [BIH 10] and with the development of biophotonic solutions [ZYS 10] will be at the crossroads of the world of services to people, home automation, telecommunications, and computer science.